.gitattributes on branch behaves unexpected. Should it be more stateless?

.gitattributes on branch behaves unexpected. Should it be more stateless?

[Max W]

Hi,

I am asking myself if git and .gitattributes should be more stateless? i.e.
whatever you have done before is irrelevant, when you reach status XYZ with your
git repo, it is EXACTLY and BINARY the same all the time and everywhere.

It took some time for me to figure out, that depending on HOW you clone, the
resulting local repo may differ. I did not expect this. I assumed that when I
clone, it is a clone (meaning: 100% identical). And that the things I have done
in my local repo before, don't have any relevance at all.



** How to reproduce **
1) create a repo, add a file with LF ending, add a .gitattributes telling git to
   do a CRLF conversion
2) clone the repo
3) on brach development, change .gitattributes to LF
4) clone again
5) clone again, directly onto the branch development (git clone -b)


** Expected result, (I) **
clone 2) and original repo 1) are bytewise identical

** Actual result (I) **
clone 2) and original repo 1) differ, 1) has LF, 2) has CRLF
as I have been warned before, I am (more or less) fine/OK with this


** Expected result, (II) **
- clone without -b (4) and clone with -b (5) are bytewise identical
- I would have expected, that whatever I do, as soon as I have a clone and I am
  on branch "development", my file should be LF
- I would have expected, that HOW you clone is irrelevant

** Actual result (II) **
without -b (4) I have a CRLF file on my disk. with -b (5) I have a LF file on my
disk. The clones are not bytewise indentical. It appears as if the
.gitattributes in branch development does not have any reliable effect.



A potential solution might be be that
- checkout
- commit (a modified .gitattribues)
- <further git commands>
  do change the files in the local repo.
As of now my understanding is that this is not how .gitattributes (or
.gitignore) are designed. .gitattributes only has influence on pushing/fetching.

I don't know if and which side effects would occur if this design would be
changed. Hence I am glad to hear any feedback on the issue described above. And
yes, I agree that this is a minor issue and that all .gitattribute things are
kind of edge cases.

Thanks and with best regards,
Max






1)
mkdir git-bug-or-feature
cd git-bug-or-feature
git init
echo "foo.bar eol=crlf" > .gitattributes
echo "hello world" > foo.bar
git add .
git commit -m "now crlf"
# [master (root-commit) 7f3f6b0] now crlf
# warning: LF will be replaced by CRLF in foo.bar.
# The file will have its original line endings in your working directory.
file foo.bar
# foo.bar: ASCII text
cd ..

2)
git clone git-bug-or-feature git-bug-or-feature_clone
cd git-bug-or-feature_clone
file foo.bar
# foo.bar: ASCII text, with CRLF line terminators
cd ..
rm -rf git-bug-or-feature_clone

3)
cd git-bug-or-feature
git branch development
git checkout development
echo "foo.bar eol=lf" > .gitattributes
git add .
git commit -m "now lf on branch development"
file foo.bar
# foo.bar: ASCII text
git checkout master
file foo.bar
# foo.bar: ASCII text
cd ..

4)
git clone git-bug-or-feature git-bug-or-feature_clone
cd git-bug-or-feature_clone
file foo.bar

Re: .gitattributes on branch behaves unexpected. Should it be more stateless?

[Philip Oakley]

> Hi,
>
> I am asking myself if git and .gitattributes should be more stateless? 
> i.e.
> whatever you have done before is irrelevant, when you reach status XYZ 
> with your
> git repo, it is EXACTLY and BINARY the same all the time and 
> everywhere.
>
> It took some time for me to figure out, that depending on HOW you 
> clone, the
> resulting local repo may differ. I did not expect this. I assumed that 
> when I
> clone, it is a clone (meaning: 100% identical). And that the things I 
> have done
> in my local repo before, don't have any relevance at all.
>

You don't say which parts you believe should be identical, nor why.

Internally Git can represent its object store in many ways based on some 
objects being 'loose' and some objects being 'packed'. However both 
styles of representation are of the same base objects and their 
contents.

Then we have external OS representation, in particular the end of line 
representations between the three main OS types Win/Mac/'nix. Git gives 
_you_ the ability the use any of these representations for the same base 
objects. Thus the object file with text "Hello World/EOL/Goodbye World" 
will have three different binary representations once you export them to 
the selected file system type (according to you .gitattributes 
settings).

If you always select LF endings for text files (both on the way in and 
on the way out of the repo), then you will get identical files on the 
different clones. Git has many settings for personalisation.

Does that help?

>
>
> ** How to reproduce **
> 1) create a repo, add a file with LF ending, add a .gitattributes 
> telling git to
>   do a CRLF conversion
> 2) clone the repo
> 3) on brach development, change .gitattributes to LF
> 4) clone again
> 5) clone again, directly onto the branch development (git clone -b)
>
>
> ** Expected result, (I) **
> clone 2) and original repo 1) are bytewise identical
>
> ** Actual result (I) **
> clone 2) and original repo 1) differ, 1) has LF, 2) has CRLF
> as I have been warned before, I am (more or less) fine/OK with this
>
>
> ** Expected result, (II) **
> - clone without -b (4) and clone with -b (5) are bytewise identical
> - I would have expected, that whatever I do, as soon as I have a clone 
> and I am
>  on branch "development", my file should be LF
> - I would have expected, that HOW you clone is irrelevant
>
> ** Actual result (II) **
> without -b (4) I have a CRLF file on my disk. with -b (5) I have a LF 
> file on my
> disk. The clones are not bytewise indentical. It appears as if the
> .gitattributes in branch development does not have any reliable 
> effect.
>
>
>
> A potential solution might be be that
> - checkout
> - commit (a modified .gitattribues)
> - <further git commands>
>  do change the files in the local repo.
> As of now my understanding is that this is not how .gitattributes (or
> .gitignore) are designed. .gitattributes only has influence on 
> pushing/fetching.
>
> I don't know if and which side effects would occur if this design 
> would be
> changed. Hence I am glad to hear any feedback on the issue described 
> above. And
> yes, I agree that this is a minor issue and that all .gitattribute 
> things are
> kind of edge cases.
>
> Thanks and with best regards,
> Max
>
>
>
>
>
>
> 1)
> mkdir git-bug-or-feature
> cd git-bug-or-feature
> git init
> echo "foo.bar eol=crlf" > .gitattributes
> echo "hello world" > foo.bar
> git add .
> git commit -m "now crlf"
> # [master (root-commit) 7f3f6b0] now crlf
> # warning: LF will be replaced by CRLF in foo.bar.
> # The file will have its original line endings in your working 
> directory.
> file foo.bar
> # foo.bar: ASCII text
> cd ..
>
> 2)
> git clone git-bug-or-feature git-bug-or-feature_clone
> cd git-bug-or-feature_clone
> file foo.bar
> # foo.bar: ASCII text, with CRLF line terminators
> cd ..
> rm -rf git-bug-or-feature_clone
>
> 3)
> cd git-bug-or-feature
> git branch development
> git checkout development
> echo "foo.bar eol=lf" > .gitattributes
> git add .
> git commit -m "now lf on branch development"
> file foo.bar
> # foo.bar: ASCII text
> git checkout master
> file foo.bar
> # foo.bar: ASCII text
> cd ..
>
> 4)
> git clone git-bug-or-feature git-bug-or-feature_clone
> cd git-bug-or-feature_clone
> file foo.bar
> --
philip 

Re: .gitattributes on branch behaves unexpected. Should it be more stateless?

[Max W]

Hi philip,

thanks for your reply.

> You don't say which parts you believe should be identical, nor why.
I expected my representation to be identical, nevertheless what path
I have taken to come there. e.g.
git clone -b <branch>
git clone; git checkout <branch>
should result in a binary-indentical representation of the files
tracked by git. But they don't.

Why did I expect this? Good question. Feels more intuitive for me.
Like "don't worry what you have done before. When your HEAD is on a
certain commit, git will make sure all your files in your filesystem
are they way you (and the other committers) want them to be".

> [..]
> Does that help?
Yes, it helped me to distinguish better between data and representation.
New understanding: .gitattributes determines how to represent data.

As .gitattributes is under git control there can be 2 versions of
.gitattributes in 2 branches. So I can tell git
- on branch foo with gitattributes * eol=LF show me all files with LF
- on branch bar with gitattributes * eol=CRLF show me all files with CRLF
But this doesn't work. The representation of the files is
determined/depending on how I cloned or fetched the repo. A "git checkout
bar" does not change the representation.

Does this help to show where my concerns / my issue is?

Best Regards,
Max



2015-01-17 14:16 GMT+01:00 Philip Oakley <philipoakley@iee.org>:
>> Hi,
>>
>> I am asking myself if git and .gitattributes should be more stateless?
>> i.e.
>> whatever you have done before is irrelevant, when you reach status XYZ
>> with your
>> git repo, it is EXACTLY and BINARY the same all the time and everywhere.
>>
>> It took some time for me to figure out, that depending on HOW you clone,
>> the
>> resulting local repo may differ. I did not expect this. I assumed that
>> when I
>> clone, it is a clone (meaning: 100% identical). And that the things I have
>> done
>> in my local repo before, don't have any relevance at all.
>>
>
> You don't say which parts you believe should be identical, nor why.
>
> Internally Git can represent its object store in many ways based on some
> objects being 'loose' and some objects being 'packed'. However both styles
> of representation are of the same base objects and their contents.
>
> Then we have external OS representation, in particular the end of line
> representations between the three main OS types Win/Mac/'nix. Git gives
> _you_ the ability the use any of these representations for the same base
> objects. Thus the object file with text "Hello World/EOL/Goodbye World" will
> have three different binary representations once you export them to the
> selected file system type (according to you .gitattributes settings).
>
> If you always select LF endings for text files (both on the way in and on
> the way out of the repo), then you will get identical files on the different
> clones. Git has many settings for personalisation.
>
> Does that help?
>
>>
>>
>> ** How to reproduce **
>> 1) create a repo, add a file with LF ending, add a .gitattributes telling
>> git to
>>   do a CRLF conversion
>> 2) clone the repo
>> 3) on brach development, change .gitattributes to LF
>> 4) clone again
>> 5) clone again, directly onto the branch development (git clone -b)
>>
>>
>> ** Expected result, (I) **
>> clone 2) and original repo 1) are bytewise identical
>>
>> ** Actual result (I) **
>> clone 2) and original repo 1) differ, 1) has LF, 2) has CRLF
>> as I have been warned before, I am (more or less) fine/OK with this
>>
>>
>> ** Expected result, (II) **
>> - clone without -b (4) and clone with -b (5) are bytewise identical
>> - I would have expected, that whatever I do, as soon as I have a clone and
>> I am
>>  on branch "development", my file should be LF
>> - I would have expected, that HOW you clone is irrelevant
>>
>> ** Actual result (II) **
>> without -b (4) I have a CRLF file on my disk. with -b (5) I have a LF file
>> on my
>> disk. The clones are not bytewise indentical. It appears as if the
>> .gitattributes in branch development does not have any reliable effect.
>>
>>
>>
>> A potential solution might be be that
>> - checkout
>> - commit (a modified .gitattribues)
>> - <further git commands>
>>  do change the files in the local repo.
>> As of now my understanding is that this is not how .gitattributes (or
>> .gitignore) are designed. .gitattributes only has influence on
>> pushing/fetching.
>>
>> I don't know if and which side effects would occur if this design would be
>> changed. Hence I am glad to hear any feedback on the issue described
>> above. And
>> yes, I agree that this is a minor issue and that all .gitattribute things
>> are
>> kind of edge cases.
>>
>> Thanks and with best regards,
>> Max
>>
>>
>>
>>
>>
>>
>> 1)
>> mkdir git-bug-or-feature
>> cd git-bug-or-feature
>> git init
>> echo "foo.bar eol=crlf" > .gitattributes
>> echo "hello world" > foo.bar
>> git add .
>> git commit -m "now crlf"
>> # [master (root-commit) 7f3f6b0] now crlf
>> # warning: LF will be replaced by CRLF in foo.bar.
>> # The file will have its original line endings in your working directory.
>> file foo.bar
>> # foo.bar: ASCII text
>> cd ..
>>
>> 2)
>> git clone git-bug-or-feature git-bug-or-feature_clone
>> cd git-bug-or-feature_clone
>> file foo.bar
>> # foo.bar: ASCII text, with CRLF line terminators
>> cd ..
>> rm -rf git-bug-or-feature_clone
>>
>> 3)
>> cd git-bug-or-feature
>> git branch development
>> git checkout development
>> echo "foo.bar eol=lf" > .gitattributes
>> git add .
>> git commit -m "now lf on branch development"
>> file foo.bar
>> # foo.bar: ASCII text
>> git checkout master
>> file foo.bar
>> # foo.bar: ASCII text
>> cd ..
>>
>> 4)
>> git clone git-bug-or-feature git-bug-or-feature_clone
>> cd git-bug-or-feature_clone
>> file foo.bar
>> --
>
> philip

Re: .gitattributes on branch behaves unexpected. Should it be more stateless?

[Philip Oakley]

Please, no top posting. It breaks the discussion flow.
From: "Max W" <max.w.7777777@googlemail.com>
> Hi philip,
>
> thanks for your reply.
>
>> You don't say which parts you believe should be identical, nor why.
> I expected my representation to be identical, nevertheless what path
> I have taken to come there. e.g.
> git clone -b <branch>
> git clone; git checkout <branch>
> should result in a binary-indentical representation of the files
> tracked by git. But they don't.

Don't forget that some of the EOL setting are also in the git config 
file(s) [global, system, local] so there may be differences from them.

Use 'git cat-file' to get the plumbing level view of the cannonical 
object content.

I am prtesuming that the ONLY differences you are seeing are end of line 
conversion changes for checkout. Is that correct.

Are there other whitespace changes happening? Is that on the way into 
the repo (git add). There are some white space settings available.

The other aspect maybe language coding settings (utf8, iso...., cp-..., 
etc).

Or is it even more than that? (Your first email suggested it was just 
line endings)

The discussion may be better helped on the googlegroups git-users forum 
git-users@googlegroups.com if this is more of a 'getting started with 
Git' problem.

>
> Why did I expect this? Good question. Feels more intuitive for me.
> Like "don't worry what you have done before. When your HEAD is on a
> certain commit, git will make sure all your files in your filesystem
> are they way you (and the other committers) want them to be".
>
>> [..]
>> Does that help?
> Yes, it helped me to distinguish better between data and 
> representation.
> New understanding: .gitattributes determines how to represent data.
>
> As .gitattributes is under git control there can be 2 versions of
> .gitattributes in 2 branches. So I can tell git
> - on branch foo with gitattributes * eol=LF show me all files with LF
> - on branch bar with gitattributes * eol=CRLF show me all files with 
> CRLF
> But this doesn't work. The representation of the files is
> determined/depending on how I cloned or fetched the repo. A "git 
> checkout
> bar" does not change the representation.
>
> Does this help to show where my concerns / my issue is?
>
> Best Regards,
> Max
>
>
>
> 2015-01-17 14:16 GMT+01:00 Philip Oakley <philipoakley@iee.org>:
>>> Hi,
>>>
>>> I am asking myself if git and .gitattributes should be more 
>>> stateless?
>>> i.e.
>>> whatever you have done before is irrelevant, when you reach status 
>>> XYZ
>>> with your
>>> git repo, it is EXACTLY and BINARY the same all the time and 
>>> everywhere.
>>>
>>> It took some time for me to figure out, that depending on HOW you 
>>> clone,
>>> the
>>> resulting local repo may differ. I did not expect this. I assumed 
>>> that
>>> when I
>>> clone, it is a clone (meaning: 100% identical). And that the things 
>>> I have
>>> done
>>> in my local repo before, don't have any relevance at all.
>>>
>>
>> You don't say which parts you believe should be identical, nor why.
>>
>> Internally Git can represent its object store in many ways based on 
>> some
>> objects being 'loose' and some objects being 'packed'. However both 
>> styles
>> of representation are of the same base objects and their contents.
>>
>> Then we have external OS representation, in particular the end of 
>> line
>> representations between the three main OS types Win/Mac/'nix. Git 
>> gives
>> _you_ the ability the use any of these representations for the same 
>> base
>> objects. Thus the object file with text "Hello World/EOL/Goodbye 
>> World" will
>> have three different binary representations once you export them to 
>> the
>> selected file system type (according to you .gitattributes settings).
>>
>> If you always select LF endings for text files (both on the way in 
>> and on
>> the way out of the repo), then you will get identical files on the 
>> different
>> clones. Git has many settings for personalisation.
>>
>> Does that help?
>>
>>>
>>>
>>> ** How to reproduce **
>>> 1) create a repo, add a file with LF ending, add a .gitattributes 
>>> telling
>>> git to
>>>   do a CRLF conversion
>>> 2) clone the repo
>>> 3) on brach development, change .gitattributes to LF
>>> 4) clone again
>>> 5) clone again, directly onto the branch development (git clone -b)
>>>
>>>
>>> ** Expected result, (I) **
>>> clone 2) and original repo 1) are bytewise identical
>>>
>>> ** Actual result (I) **
>>> clone 2) and original repo 1) differ, 1) has LF, 2) has CRLF
>>> as I have been warned before, I am (more or less) fine/OK with this
>>>
>>>
>>> ** Expected result, (II) **
>>> - clone without -b (4) and clone with -b (5) are bytewise identical
>>> - I would have expected, that whatever I do, as soon as I have a 
>>> clone and
>>> I am
>>>  on branch "development", my file should be LF
>>> - I would have expected, that HOW you clone is irrelevant
>>>
>>> ** Actual result (II) **
>>> without -b (4) I have a CRLF file on my disk. with -b (5) I have a 
>>> LF file
>>> on my
>>> disk. The clones are not bytewise indentical. It appears as if the
>>> .gitattributes in branch development does not have any reliable 
>>> effect.
>>>
>>>
>>>
>>> A potential solution might be be that
>>> - checkout
>>> - commit (a modified .gitattribues)
>>> - <further git commands>
>>>  do change the files in the local repo.
>>> As of now my understanding is that this is not how .gitattributes 
>>> (or
>>> .gitignore) are designed. .gitattributes only has influence on
>>> pushing/fetching.
>>>
>>> I don't know if and which side effects would occur if this design 
>>> would be
>>> changed. Hence I am glad to hear any feedback on the issue described
>>> above. And
>>> yes, I agree that this is a minor issue and that all .gitattribute 
>>> things
>>> are
>>> kind of edge cases.
>>>
>>> Thanks and with best regards,
>>> Max
>>>
>>>
>>>
>>>
>>>
>>>
>>> 1)
>>> mkdir git-bug-or-feature
>>> cd git-bug-or-feature
>>> git init
>>> echo "foo.bar eol=crlf" > .gitattributes
>>> echo "hello world" > foo.bar
>>> git add .
>>> git commit -m "now crlf"
>>> # [master (root-commit) 7f3f6b0] now crlf
>>> # warning: LF will be replaced by CRLF in foo.bar.
>>> # The file will have its original line endings in your working 
>>> directory.
>>> file foo.bar
>>> # foo.bar: ASCII text
>>> cd ..
>>>
>>> 2)
>>> git clone git-bug-or-feature git-bug-or-feature_clone
>>> cd git-bug-or-feature_clone
>>> file foo.bar
>>> # foo.bar: ASCII text, with CRLF line terminators
>>> cd ..
>>> rm -rf git-bug-or-feature_clone
>>>
>>> 3)
>>> cd git-bug-or-feature
>>> git branch development
>>> git checkout development
>>> echo "foo.bar eol=lf" > .gitattributes
>>> git add .
>>> git commit -m "now lf on branch development"
>>> file foo.bar
>>> # foo.bar: ASCII text
>>> git checkout master
>>> file foo.bar
>>> # foo.bar: ASCII text
>>> cd ..
>>>
>>> 4)
>>> git clone git-bug-or-feature git-bug-or-feature_clone
>>> cd git-bug-or-feature_clone
>>> file foo.bar
>>> --
>>
>> philip
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